1. Field of the Invention
The present invention relates to a card-type portable device, for use in, for example, various electronic devices such as a personal computer and a digital camera.
2. Description of the Related Art
In recent years, multimedia cards and SD memory cards using flash memory have been used as storage media for storing a large amount of data in digital video cameras, digital cameras, mobile terminals, and other electronic devices. Each of these cards is inserted into a card insertion slot of a digital video camera or other electronic device, and after data is stored on the card, the card can be loaded, for example, in a personal computer such that data may be edited.
Also, a communication card having a radio communication function may be necessary in order to receive data distribution of music from a base station of a mobile phone (for example, a personal handyphone system (PHS)) to a mobile terminal such as a personal digital assistants (personal data assistants) (PDA). The external dimensions and electrical characteristics of a serial connection of this communication card correspond to those of, for example, an SD card. Particularly, in terminal electrodes which mechanically contact the inside of the card insertion slot, the number of terminal electrodes, the alignment pattern, and the distance from the card surface to the terminal electrodes are specified.
In order to fulfill these specifications, a circuit board 1 is provided in the center of a casing 2 in the communication card, as shown in the sectional view of FIG. 16. That is, the circuit board 1 is provided in the casing 2 with an end surface thereof being exposed. The location of the circuit board 1 is set such that the end surface of the circuit board 1 is located lower than the outer surface 3 of the casing 2 by the height h. On the exposed end surface 4 of the circuit board 1, eight terminal electrodes 5 are aligned along a line in the width direction of the circuit board 1, as shown in the plan view of FIG. 17. One terminal electrode 6 is arranged offset backwardly from the remaining terminal electrodes. Further, inside the casing 2, electronic components 7, such as an interface circuit, a controller, a baseband processing circuit, an IC such as a memory, an RF circuit, and an antenna, are mounted on the both surfaces of the circuit board 1.
However, the thickness of an SD card is specified as 2.1 mm. When the circuit board 1 is provided in the center of the casing 2, tall electronic components 7 cannot be mounted on the circuit board 1 because the space defined by the board surface of the circuit board 1 and the casing 2 is less than the tall electronic components 7. Accordingly, if the tall electronic components 7 are mounted on the circuit board 1, the thickness of the casing 2 of the communication card increases and the communication card does not conform to the specifications.
Further, the communication card is repeatedly inserted into the card insertion slot of equipment such as a PDA and is brought into contact with an internal terminal. Thus, the card is thickly gold-plated in order to decrease the contact resistance of the terminal electrodes 5 and 6 and to increase the durability against mechanical friction. However, by gold-plating the entire conductor portion including the wiring pattern of the circuit board 1, the cost increases. Also, when the above-described electronic components 7 are mounted via solder, gold diffuses in the solder and the strength of the solder connection reduces, which results in reduced reliability of electronic component mounting. Gold-plating may be selectively performed on only the terminal electrodes 5 and 6 provided on the circuit board 1 in order to reduce the amount of gold used, however in that case, the manufacturing process is complicated and the manufacture costs increase.
In order to overcome the above-described problems, preferred embodiments of the present invention provide a card-type portable device in which the height position of terminal electrodes conforms to the specification of a card-type portable device and the circuit board can be freely arranged inside a casing.
A card-type portable device according to a preferred embodiment of the present invention includes a circuit board for mounting electronic components thereon to define a circuit, a casing for accommodating the circuit board, a portion of the circuit board being exposed from the case, and a terminal board including a surface provided with terminal electrodes. The terminal board is mounted on the circuit board, the terminal electrodes is arranged relative to the exposed portion of the circuit board and the terminal electrodes are arranged at a height location that is different from the height location of the board surface of the circuit board.
The casing includes a pair of walls which face each other with a space therebetween and which are substantially parallel to each other, the circuit board is provided along the inner surface of one of the pair of walls, the terminal electrode surface of the terminal board is arranged so as to be substantially parallel to the surface of the circuit board, and the height position of the terminal electrode surface is set based on the thickness of the terminal board.
The surface of the terminal board includes the plurality of terminal electrodes, the bottom surface of the terminal board includes a plurality of connection electrodes connected to the terminal electrodes of the terminal board, and the terminal board mounting portion of the circuit board includes connection patterns which face and are connected to the connection electrodes of the terminal board.
The terminal electrodes and the connection electrodes of the terminal board are preferably defined by different conductors.
Each of the connection electrodes of the terminal board and each of the connection patterns of the circuit board includes a plurality of connection lands and coupling lands for mutually coupling the connection lands.
The connection electrodes of the terminal board and the connection patterns of the circuit board are covered with resist, the resist is provided with openings in the portions of the connection lands such that the connection lands are exposed, and the connection lands arranged vertically are soldered.
A solder ball is attached to each of the connection lands of the connection electrodes, and the connection lands of the connection electrodes and the connection lands of the connection patterns that face each other are bonded via the solder balls.
The plurality of terminal electrodes and the plurality of connection electrodes provided on the terminal board are aligned, the circuit board is provided with the plurality of connection patterns corresponding to the alignment positions of the connection electrodes, and the width of the terminal board in the alignment direction of the terminal electrodes is greater than the width of the circuit board in the alignment direction of the connection patterns.
The electronic components are mounted on the bottom surface of the terminal board and the terminal board mounting area of the circuit board is provided with recessed portions for mounting the electronic components therein.
The difference between the coefficient of linear expansion in the direction along the board surface of the terminal board and the coefficient of linear expansion in the direction along the board surface of the circuit board is about 26.6 ppm/xc2x0 C. or less.
The material of the terminal board and the material of the circuit board preferably have the same coefficient of linear expansion in the direction along the board surface.
According to another preferred embodiment of the present invention, the card-type portable device is preferably a communication card having a communication function.
Other feature, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.